Evolution Flashcards
Species vary locally
Closely related but different species occupying different habitat in same geographic area
Evolutionary theory explains existence of
Homologous structures adapted to different purposes as the result of descent with modification
Evidence of common descent
Universal genetic code
Homologous molecules
Grants
Documented that natural selection in Galapagos finches takes place frequently
Variation within a species increases the likelihood of the species adapting to and surging environmental change
Variation
Raw material for natural selection
Techniques of molecular genetics used
To form and test hypotheses about heritable variation and natural selection
Natural selection never acts on
Genes because the entire organism either survives or doesn’t
Allele frequency has nothing to do with
Dominant and recessive
3 sources of genetic variation
Mutation
Genetic recombination
Lateral gene transfer
We are born with
Approx 300 mutations
Most heritable mutations come from genetic recombination
Independent assortment in humans results in
8.4 million gene combinations
Lateral gene transfer
Passing of genes from one organism to another that is not its offspring
Important in evolution of antibiotic resistance in bacteria
Number of phenotype a for trait depends on
Number of genes that control it
Single gene trait- 1-3 phenotypes
Polygenic trait- many possible genotype and even more phenotypes (bell shaped curve = normal distribution)
Phenotypic ratios determined by
Frequency of alleles and whether alleles are dominant or recessive
Evolutionary fitness
Success in passing genes to next generation
Evolutionary adaptation
Any genetically controlled trait that increases an individuals ability to pass along its alleles
Natural selection on single gene trait
Change in allele and phenotype frequencies
Natural selection on polygenic trait
Affect relative fitness if phenotypes and can result in
Disruptive selection
Directional selection
Stabilizing selection
Genetic drift
Random change in allele frequency
Bottleneck effect
Founder effect
Meiosis and fertilization by themselves don’t change
Allele frequencies
Hardy Weinberg principle
(Frequency of AA) + (frequency of Aa) + (frequency of aa) = 100% and
(Frequency of A) + (frequency of a) = 1
Genetic equilibrium
Conditions that disrupt genetic equilibrium
No random mating Small population size Immigration or emigration Mutations Natural selection Shuffling of genes altering frequencies of alleles
Species
Population or group of populations whose members can interbreed and produce fertile offspring
Speciation in Galapagos finches
Founding of new populations Geographic isolation Changes in new populations gene pool Behavioral isolation Ecological competition Repetition
Molecular clock
Uses mutation rates in DNA to estimate that 2 species have been evolving independently
Neutral mutations
No effect on phenotype
Accumulate in DNA of different species at about the same rate
More differences between DNA of two species…
More time passed since they shared a common ancestor
Many different clocks which allow researchers to…
Time evolutionary events
Accuracy checked by trying to estimate how often mutations occur b
New genes can evolve through
Duplication and modification of existing genes
Homologous chromosomes exchange DNA during
Crossing over
sometimes involves unequal swapping of DNA so one chromosome gets extra DNA varying from part of a gene or a full gene to a longer length of chromosome)
Extra copies of a gene can undergo
Mutations that change their function
The original gene remains and is not affected
Multiple copies of a duplicated gene can turn into a group of related genes called a gene family (produced similar proteins)
Hox genes
Embryo development and size and shape of structures
Small changes in activity during embryo logical development can produce large changes
Species vary globally
Seemingly similar but unrelated species living in ecologically similar environments
Early scientific names
Extremely long
Difficult to standardize
Linnaeus
Developed binomial nomenclature
2nd part of scientific name is unique to each organism
Systematics
Naming and grouping organisms
Goal is to organize living things into group (taxa) with biological meaning
Linnaean classification system
Developed over ime into:
Species, genus, family, order, class, phylum, kingdom
Strategy was based on similarities and differences which causes issues
Phylogeny
The evolutionary history of lineages
Goal of phylogenetic systematics- to group species to reflect lines of evolutionary descent
Larger tax on
Farther back in time members shared a common ancestor
Clade
Group of species that includes one common ancestor and all descendants
Must be mono phyletic
Cladistic analysis
Compared traits to determine order groups of organisms branches off from common ancestors
Systematists cause about using absence of a trait in analyses because
Distantly related groups can lose same trait
Similarities and differences in DNA can be used to
Develop hypotheses about evolutionary relationships
Makes evolutionary trees more accurate
Used when anatomical traits can’t provide enough evidence
How kingdoms changes
Plantae and animalia to
Monera Protista fungi plantae and animalia to
Eubacteria archaebacteria Protista fungi plantae animalia
Domain
Larger more inclusive category than kingdom
Bacteria
Archae
Eukarya
Domain bacteria
Unicellular Prokaryotic Thick rigid walls with peptidoglycan and cell membrane Ecologically diverse Corresponds to kingdom eubacteria
Domain archaea
Unicellular Prokaryotic Live in extreme environments Many survive only in absence of oxygen Cell membranes of unusual lipids Kingdom archaebacteria
Domain Eukarya
All organisms with nucleus
Contains “Protista” plantae and animalia
Protista
Unicellular eukaryotes
Brown algae is multicellular
Fungi
Heterotrophs Cell walls with chitin Feed on dead decaying organism Secrete digestive enzymes into food source and absorb molecules broken down from enzymes Some are multicellular
Plantae
Autotrophs Cell walls with cellulose Photosynthesis through chlorophyll Nonmotile Sister group to red algae
Animalia
Multicellular Heterotrophic No cell walls Most can move Diverse
Carbon14
Limited to organisms that lived in last 60,000 years
Half life of 5730 years
Half life
Time required for half radioactive atoms in a sample to decay
Length of half lives and uses
Elements with short half lives- recent fossils
Long Half lives- older fossils
Geologic time scale
Time line of earths history
Eons
Eras
Periods
More than 99% Of all species that lives on earth are now
Extinct
Macro evolutionary patterns
Grand transformations in anatomy, Phylogeny, Ecology, and Behavior, which take place in clashes larger than one species
Classification of fossils needed to
Learn about macro evolutionary patterns
Environmental conditions change
Processes of evolutionary change enable some species to adapt and thrive
Some Clades are successful because of species diversity
Species diversity
Raw material for macro evolutionary change within Clades
Background extinction
Species become extinct because of slow process of natural selection
Gradualism
Evolution being slow and steady
Punctuated equilibrium
Equilibrium that is interrupted by brief periods of rapid change
Rapid evolution may occur after
A small population becomes isolated from main population
Adaptive radiation
Process by which single species or small group evolves “rapidly” into several different forms that live in different ways
Convergent evolution
Produced similar structures or characteristics in distantly related organisms (e. g. Mammals that feed on ants)
Co evolution
Process by which two species evolve in response to changes in each other over time
Earths early atmosphere
Little or no oxygen
Composed of carbon dioxide, water vapor, nitrogen, carbon monoxide, hydrogen sulfide and cyanide
Oceans brown because of iron
RNA world hypothesis
RNA existed before DNA
Steps led to DNA directed protein synthesis
Microspheres
Some characteristics of living systems
Photosynthetic bacteria
Added oxygen to atmosphere
Oxygen and iron in oceans lead to rust that sank and changed ocean color
Color of sky changed
Endosymbiotic theory
Symbiotic relationship evolved over time between primitive eukaryotic cells and prokaryotic cells within them
Prokaryotic cells evolved into mitochondria and chloroplasts
